"Failed encounter again"

For the second phone call appointment in a row. I was called more than half an hour before my appointment time. I have to schedule my availability to make my self availabke so i missed this call. A message was left for me to call back but the phone lines are closed 1200-1630 and my appointment was meant to bw 1320.

If i arrived 30 minitues before my appointment time in person I certainly wouldnt be seen early so why am i expected to be available before a scheduled call time